This is in response to the announcement that CREG DCCP3, In Vitro Chemical Carcinogenesis is open for competitive renewal (Letter of Dr. Virginia Dunkel dated 3/8/78). We propose to continue our integrated study of oncogenic transformation, DNA damage, synthesis and repair, mutation, and cytotoxicity in C3H/10T1/2 cells treated with four alkylating agents and four polycyclic aromatic hydrocarbons of different oncogenic potency. We have already generated dose response data for the above parameters in cells treated with alkylating agents, and with that data it has proved possible to assign biological effects to molecular lesions. We have yet to quantitate oncogenic transformation with alkylating agents, and to measure alkylation products in DNA. Completion of these projects will provide 1) information on the role of DNA damage in oncogenesis; 2) a cell line (C3H/10T1/2 cells), which, when coupled with metabolic activation, can be used for early identification of most classes of mutagens and carcinogens.